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The first thing I decided to do was transplant the guts of the old unit – the PC104 stack and floppy drive – into a newer, larger case, along with a new power supply to replace the one that wasn't working reliably.  This would give me more room inside, so that the secondary power supply for the PIC programmer could be brought inside the unit, and would also give me enough room on the top of the unit to mount the PIC programmer.  I also wanted enough room to add a fan, for better air circulation; apparently, the reason they had opened the unit up "once or twice" was to replace the power supply...  and now here it was needing replacement again.  An overheating issue seemed the most likely cause.  I mounted the fan so that it would pull air into the case and blow directly on the PSU's heat sink.

The extra air circulation won't exactly hurt the PC/104 computer, either. Even a lowly 486 chip can get fairly warm in operation...

Bringing the PIC programmer's wall-wart supply inside involved a bit of work.  First, I cracked open the plastic case using a hacksaw and a couple of screwdrivers; then, I cut off the wires going to the AC-plug blades, cemented the transformer and rectifier board to the interior of the case, then connected the transformer's primary side to the same AC wires feeding the +5V PSU.  Then, just for the heck of it, I covered up the transplanted guts of the wall-wart supply with the upper half of the sawn-apart case for, uh, safety reasons.  Yeah, that's it.  Don't want to leave any exposed AC connections, right?

Since the new cooling fan requires 12VDC, and the main power supply doesn't have a 12V output, the 18V wall-wart supply does double-duty by feeding an LM7812 +12V regulator to run the fan, as well as running the PIC programming board.